Battery case, secondary battery, and method for manufacturing same

ABSTRACT

The present invention relates to a secondary battery. The secondary battery comprises: an electrode assembly having a through-hole; and a battery case accommodating the electrode assembly and having a through-type opening into which the through-hole is inserted, wherein the battery case comprises: a lower case comprising an accommodation part accommodating the electrode assembly and a lower inner sealing part having the through-type opening into which the through-hole is inserted; and an upper case comprising a cover part coupled to an upper portion of the lower case to finish the accommodation part and an upper inner sealing part having a coupling hole to which a front end of the lower inner sealing part is coupled.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of the priority of KoreanPatent Application Nos. 2015-0180248, filed on Dec. 16, 2015, and2016-0157558, filed on Nov. 24, 2016, which are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a battery case, a secondary battery anda method for manufacturing the same, and more particularly, to a batterycase which is maximized in space utilization of an opening, a secondarybattery and a method for manufacturing the same.

BACKGROUND ART

In general, secondary batteries refer to chargeable and dischargeablebatteries, unlike primary batteries that are not chargeable. Such asecondary battery is being widely used in the high-tech electronicfields such as mobile phones, notebook computers, and camcorders.

In recent years, a secondary battery having an opening that verticallypasses through a central portion thereof is disclosed.

DISCLOSURE OF THE INVENTION Technical Problem

A secondary battery comprises an electrode assembly having a verticalthrough-hole and a pouch case accommodating the electrode assembly andhaving an opening passing through the through-hole.

Here, the pouch case comprises an outer sealing surface sealing an outeredge and an inner sealing surface sealing a circumferential surface ofthe opening. The outer sealing surface and the inner sealing surface areheated to be sealed in a state in which top and bottom surfaces arepress-fitted at the same time.

However, in the above-described secondary battery, since the outersealing surface and the inner sealing surface are disposed on theopening, a space of the opening is significantly reduced to deterioratespace utilization of the opening.

The present invention has been made to solve the abovementioned problem,and an object of the present invention is to provide a battery case inwhich a pouch case having an opening is improved in structure to preventa space of the opening from being reduced and thereby to maximize spaceutilization, a secondary battery and a method for manufacturing thesame.

Technical Solution

To achieve the above-described object, a secondary battery according toan embodiment of the present invention comprises: an electrode assemblyhaving a through-hole; and a battery case accommodating the electrodeassembly and having a through-type opening into which the through-holeis inserted, wherein the battery case comprises: a lower case comprisingan accommodation part accommodating the electrode assembly and a lowerinner sealing part having the through-type opening into which thethrough-hole is inserted; and an upper case comprising a cover partcoupled to an upper portion of the lower case to finish theaccommodation part and an upper inner sealing part having a couplinghole to which a front end of the lower inner sealing part is coupled.

The upper inner sealing part may have an inner sealing surface havingthe coupling hole to which the front end of the lower inner sealing partis coupled and a connection surface having an inner end coupled to abottom surface of the inner sealing surface and an outer end connectedto the cover part, and an opening groove may be defined between theinner sealing surface and the connection surface.

The lower inner sealing part disposed on the through-type opening andthe inner sealing surface disposed on the opening groove may bepress-fitted at the same time to seal the lower inner sealing part andthe upper inner sealing part.

The front end of the lower inner sealing part and a top surface of theupper case may have the same height.

A top surface of the upper inner sealing part and a top surface of thecover part may have the same height.

The electrode assembly may comprise a plurality of radical units havingthrough-holes that gradually increase in size, and the plurality ofradical units may be stacked upward in order from the radical unithaving the smallest size to the radical unit having the largest size,and the upper inner sealing part may be inserted into a space between aninner surface of the through-hole of the lowermost radical unit and aninner surface of the uppermost radical unit of the radical units.

A connection part connecting ends of the lower case and the upper case,which correspond to each other, to each other may be provided.

A lower outer sealing part and an upper outer sealing part, which aresealed to each other, may be disposed on remaining ends except for theends of the lower case and the upper case, respectively.

A method for manufacturing a secondary battery according to anembodiment of the present invention comprises: a step (a) ofmanufacturing an electrode assembly having a through-hole; a step (b) ofmanufacturing a battery case comprising a lower case and an upper case,which are folded with respect to an end, wherein the lower casecomprises an accommodation part accommodating the electrode assembly anda lower inner sealing part inserted into the through-hole and having aninsertion groove, and the upper case comprises a cover part finishingthe accommodation part and an upper inner sealing part having a couplinghole to which a front end of the lower inner sealing part is coupled; astep (c) of inserting the electrode assembly between the lower case andthe upper case; a step (d) of sealing the coupled portion between thelower inner sealing part and the upper inner sealing part; and a step(e) of forming cutting a bottom surface of the insertion groove of thelower inner sealing part and a surface of the upper inner sealing part,which are closely attached to each other, to form a through-type openinginto which the through-hole is inserted.

The upper inner sealing part may have an inner sealing surface havingthe coupling hole to which the front end of the lower inner sealing partis coupled and a connection surface having an inner end coupled to abottom surface of the inner sealing surface and an outer end connectedto the cover part, and an opening groove may be defined between theinner sealing surface and the connection surface.

In the step (d), the lower inner sealing part disposed on the insertiongroove and the inner sealing surface disposed on the opening groove maybe press-fitted at the same time to seal the lower inner sealing partand the upper inner sealing part.

In step (b), a connection part connecting the lower case to the uppercase may be disposed on ends of the lower case and the upper case, whichcorrespond to each other, a lower outer sealing part and an upper outersealing part, which are sealed to each other, may be disposed onremaining ends except for the ends of the lower case and the upper case,respectively, and the step (d) may further comprise a process of sealingthe lower outer sealing part and the upper outer sealing part.

The step (a) may comprise a step of manufacturing a plurality of radicalunits having through-holes that gradually increase in size and a step ofstacking the plurality of radical units upward in order from the radicalunit having the smallest size to the radical unit having the largestsize.

A battery case according to an embodiment of the present inventioncomprises: a lower case comprising an accommodation part and a lowerinner sealing part provided at a center of the accommodation part andhaving a through-type opening; and an upper case comprising a cover partcoupled to an upper portion of the lower case to finish theaccommodation part and an upper inner sealing part having a couplinghole to which a front end of the lower inner sealing part is coupled.

The upper inner sealing part may have an inner sealing surface havingthe coupling hole to which the front end of the lower inner sealing partis coupled and a connection surface having an inner end coupled to abottom surface of the inner sealing surface and an outer end connectedto the cover part, and an opening groove may be defined between theinner sealing surface and the connection surface.

The lower inner sealing part disposed on the through-type opening andthe inner sealing surface disposed on the opening groove may bepress-fitted at the same time to seal the lower inner sealing part andthe upper inner sealing part.

The lower case and the upper case may comprise a connection partconnecting ends of the lower case and the upper case, which correspondto each other, to each other and a lower outer sealing part and an upperouter sealing part, which are sealed to each other and respectivelydisposed on remaining ends except for the ends of the lower case and theupper case.

Advantageous Effects

The secondary battery according to the present invention may comprisethe battery case having the through-type opening that vertically passesto secure the large space of the through-type opening and improve thespace utilization.

Also, the secondary battery according to the present invention maycomprise the battery case comprising the lower case and the upper case.The lower case may comprise the lower inner sealing part having thethrough-type opening, and the upper case may comprise the upper innersealing part into which the lower inner sealing part is inserted andcoupled. Thus, the large opening of the through-type opening may besecured.

Also, in the battery case according to the present invention, the frontend of the lower inner sealing part and the top surface of the uppercase may be provided at the same height to prevent the secondary batteryfrom increasing in thickness.

Also, in the battery case according to the present invention, the upperinner sealing part may have the inner sealing surface and the connectionsurface to more easily seal the lower inner sealing part and the upperinner sealing part.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a secondary battery according to anembodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1.

FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1.

FIG. 4 is a flowchart illustrating a method for manufacturing thesecondary battery according to an embodiment of the present invention.

FIGS. 5 to 9 are views illustrating a method for manufacturing thesecondary battery according to an embodiment of the present invention,wherein, FIG. 5 is a view illustrating a step of manufacturing anelectrode assembly, FIG. 6 is a view illustrating a step ofmanufacturing a battery case, FIG. 7 is a view illustrating a step ofinserting the electrode assembly into the battery case, FIG. 8 is a viewillustrating a step of sealing the battery case, and FIG. 9 is a viewillustrating a step of forming a through-type opening.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings in such a manner thatthe technical idea of the present invention may easily be carried out bya person with ordinary skill in the art to which the invention pertains.The present invention may, however, be embodied in different forms andshould not be construed as limited to the embodiments set forth herein.In the drawings, anything unnecessary for describing the presentinvention will be omitted for clarity, and also like reference numeralsin the drawings denote like elements.

Secondary Battery According to an Embodiment

As illustrated in FIGS. 1 to 3, a secondary battery 100 according to anembodiment of the present invention comprises an electrode assembly 110having a through-hole and a battery case 120 accommodating the electrodeassembly 110 and having a through-type opening into which thethrough-hole is inserted.

Electrode Assembly

Referring to FIG. 2, the electrode assembly 110 comprises a plurality ofradical units 111 that are staked in a vertical direction. Each of theplurality of radical units 111 has a structure in which a plurality ofelectrodes and a plurality of separators are alternately stacked.

Here, the electrode assembly 110 has a through-hole 110 a that passes ina direction in which the radical units 111 are stacked. That is, thethrough-holes defined in the plurality of radical units 111 are stackedto be vertically connected to each other to manufacture the electrodeassembly 110 having the through-hole 110 a.

The through-holes defined in the plurality of radical units 111 may havedifferent sizes, i.e., sizes that gradually increases. That is, theradical units 111 may be stacked upward from the radical unit 111 havingthe smallest through-hole to the radical unit 111 having the largestthrough-hole. Thus, the electrode assembly 110 may have the through-hole110 a having an approximately stepped reversed trapezoidal shape incross-section.

Battery Case

The battery case 120 accommodates the electrode assembly 110 to besealed. The battery case 120 comprises a lower case 121 and an uppercase 122, which are respectively disposed on top and bottom surfaces ofthe electrode assembly 110 and coupled to each other to accommodate theelectrode assembly 110. Here, the battery case 120 may have athrough-type opening 120 a into which the through-hole 110 a isinserted.

The lower case 121 comprises an accommodation part accommodating theelectrode assembly 110 and a lower inner sealing part 121 b disposed ata center of the accommodation part 121 a and having the through-typeopening 120 a into which the through-hole is inserted.

Here, the lower inner sealing part 121 b has a vertical through-typeopening 120 a that extends in the same direction as the through-hole 110a. An inner circumferential surface 121 a-1 of the through-type opening120 a may be defined as a vertical surface to secure a large space.

Also, a front end of the lower inner sealing part 121 b may extend up toa top surface of the through-hole 110 a, i.e., at the same height as theupper case 122 to maximally secure a vertical space of the through-typeopening 120 a.

The upper case 122 is coupled to a top surface of the lower case 121.The upper case 122 comprises a cover part 122 a coupled to an upperportion of the lower case 121 to finish the accommodation part 121 a andan upper inner sealing part 122 b having a coupling hole 122 b-1 towhich the front end of the lower inner sealing part 121 b inserted intothe through-hole 110 a is coupled. That is, the upper inner sealing part122 b has a coupling hole 122 b-1 coupled to the lower inner sealingpart 121 b to improve coupling between the upper inner sealing part 122b and the lower inner sealing part 121 b.

The upper inner sealing part 122 b extends downward from the cover part122 a. Here, a space is required for press-fitting and thermally fusingthe lower inner sealing part 121 b and the upper inner sealing part 122b, which are closely attached to each other. Here, the lower innersealing part 121 b may be press-fitted in a direction of the upper innersealing part 122 b through the opening 120 a. On the other hand, theupper inner sealing part may not be press-fitted in a direction of thelower inner sealing part 121 b.

Thus, the upper inner sealing part 122 b has a shape capable of beingpress-fitted in the direction of the lower inner sealing part 121 b toperform a sealing operation. For example, the upper inner sealing part122 b is provided in a ‘U’ or ‘V’ shape in cross-section from the coverpart 122 a to define an opening groove 122 c that is opened upward.Thus, the upper inner sealing part 122 b may be press-fitted in thedirection of the lower inner sealing part 121 b through the openinggroove 122 c to perform the sealing operation.

In more detail, the upper inner sealing part 122 b has an inner sealingsurface 122 b-2 having a coupling hole 122 b-1 to which the front end ofthe lower inner sealing part 121 b is coupled and a connection surface122 b-3 having an inner end coupled to a bottom surface of the innersealing surface 122 b-2 and an outer end folded upward and coupled tothe cover part 122 a.

That is, the upper inner sealing part 122 b has an inner sealing surface122 b-2 and a connection surface 122 b-3. An opening groove 122 c isdefined between the inner sealing surface 122 b-2 and the connectionsurface 122 b-3. The inner sealing surface 122 b-3 disposed in theopening groove 122 c is press-fitted in the direction of the lower innersealing part 121 b to perform the sealing operation.

The upper inner sealing part 122 b having the inner sealing surface 122b-2 and the connection surface 122 b-3 may protrude downward. The upperinner sealing part 122 b protruding downward is inserted into a spacebetween an inner surface of the through-hole of the lowermost radicalunit 111 of the electrode assembly 110 and an inner surface of thethrough-hole of the uppermost radical unit 111. Thus, the upper innersealing part 122 b may be provided without deforming the shape of theelectrode assembly 110 or the shape of the battery case 120.

The battery case 120 having the above-described constituents may havethe through-type opening 120 a into which the through-hole 110 a of theelectrode assembly 110 is inserted. Particularly, the through-typeopening 120 a may secure the large space and improve the spaceutilization because a protruding or projecting portion does not exist ona circumferential surface 121 b-1.

The battery case 120 comprises a connection part 123 connecting ends ofthe lower case 121 and the upper case 122 to each other. That is, in thebattery case 120, the upper case 122 may be folded toward the lower case121 by using the connection part 123 as a center so that the upper case122 and the lower case 121 are disposed to correspond to each other.

As illustrated in FIG. 3, the battery case 120 comprises a lower outersealing part 121 c and an upper outer sealing part 122 d, which aresealed to each other, are disposed on the remaining ends except for theends of the lower case 121 and the upper case 122 to improve sealabilityof the lower case 121 and the upper case 122.

The top surface of the upper inner sealing part 122 b and the topsurface of the cover part 122 a have the same height to prevent thebattery case 120 from increasing in thickness.

Thus, the battery case 100 according to an embodiment of the presentinvention may secure the large space of the through-type opening 120 adefined in the battery case 120 to improve the space utilization.

In the secondary battery 100 according to an embodiment of the presentinvention, only the battery case 120 may be commercialized as a separateproduct.

Battery Case According to an Embodiment

That is, the battery case 120 according to an embodiment of the presentinvention comprises an accommodation part 121 a, a lower case 121comprising a lower inner sealing part 121 b disposed at a center of theaccommodation part 121 a and having a through-type opening 120 a, acover part 122 a coupled to an upper portion of the lower case 121 tofinish the accommodation part 121 a, and an upper case 122 comprising anupper inner sealing part 122 b having a coupling hole 122 b-1 to which afront end of the lower inner sealing part 121 b is coupled.

Method for Manufacturing Secondary Battery According to an Embodiment

Hereinafter, a method for a secondary battery according to an embodimentof the present invention will be described.

As illustrated in FIGS. 4 to 9, a method for manufacturing a secondarybattery according to an embodiment of the present invention comprises astep (a) of manufacturing an electrode assembly having a through-hole, astep (b) of manufacturing a battery case comprising a lower case and anupper case, which are folded with respect to an end, wherein the lowercase comprises an accommodation part accommodating the electrodeassembly and a lower inner sealing part inserted into the through-holeand having an insertion groove, and the upper case comprises a coverpart finishing the accommodation part and an upper inner sealing parthaving a coupling hole to which a front end of the lower inner sealingpart is coupled, a step (c) of inserting the electrode assembly betweenthe lower case and the upper case, a step (d) of sealing the coupledportion between the lower inner sealing part and the upper inner sealingpart, and a step (e) of forming cutting a bottom surface of theinsertion groove of the lower inner sealing part and a surface of theupper inner sealing part, which are closely attached to each other, toform a through-type opening into which the through-hole is inserted.

Step (a)

As illustrated in FIG. 5, the step (a) is a step of manufacturing theelectrode assembly and comprises a process of manufacturing a pluralityof radical units and a process of stacking the plurality of radicalunits.

In the process of manufacturing the radical units, a plurality ofelectrodes, each of which has a through-hole, and a plurality ofseparators, each of which has a through-hole, are alternately stacked tomanufacture a radical unit 111. Here, the through-holes of theelectrodes and the through-holes of the separators are connected to eachother to provide a through-hole in the radical unit 111.

In the process of manufacturing the radical unit, a plurality of radicalunits 111 having the through-holes that gradually increase in size aremanufactured.

In the process of stacking the radical units, the plurality of radicalunits 111 are stacked to manufacture an electrode assembly 110. Here,the plurality of radical units 111 are stacked upward from the radicalunit 111 having the smallest through-hole to the radical unit 111 havingthe largest through-hole. Thus, the electrode assembly 110 has athrough-hole 110 a that gradually increases in size upward. That is,referring to FIG. 5, the through-hole 110 a may have a shape thatincreases in size upward in stages.

Step (b)

As illustrated in FIG. 6, the step (b) is a step of manufacturing thebattery case. In the step (b), a battery case 120 comprising a lowercase 121 and an upper case 122, of which ends are connected to eachother by a connection part 123, is manufactured.

That is, the battery case 120 is folded so that the lower case 121 andthe upper case 122 overlap each other with respect to the endsconnecting the lower case 121 to the upper case 122.

Here, the lower case 121 comprises an accommodation part 121 a having anaccommodation space in a top surface thereof to accommodate theelectrode assembly 110 and a lower inner sealing part 121 b disposed ona surface (when a bottom surface when viewed in FIG. 6) of theaccommodation part 121 a, extending upward to be inserted into thethrough-hole 110 a, and having an insertion groove that is openeddownward.

The upper case 122 comprises a cover part 122 a finishing theaccommodation part 121 a and an upper inner sealing part 122 b having acoupling hole 122 b-1 to which a front end of the lower inner sealingpart 121 b is coupled.

Here, the upper inner sealing part 122 b has an inner sealing surface122 b-2 having a coupling hole 122 b-1 to which the front end of thelower inner sealing part 121 b is coupled and a connection surface 122b-3 having an inner end coupled to a bottom surface of the inner sealingsurface 122 b-2 and an outer end folded upward and coupled to the coverpart 122 a. An opening groove 122 c is formed between the inner sealingsurface 122 b-2 and the connection surface 122 b-3.

Also, a lower outer sealing part 121 c and an upper outer sealing part122 d are formed on remaining ends except for the ends of the lower case121 and the upper case 122, respectively.

Step (c)

As illustrated in FIG. 7, the step (c) is a step for inserting theelectrode assembly into the battery case. In the step (c), the electrodeassembly 110 is inserted into the accommodation part 121 a of the lowercase 121. Here, the lower inner sealing part 121 b of the lower case 121is inserted into the through-hole 110 a of the electrode assembly 110and then coupled to the coupling hole 121 b-1 of the upper case 122.

Step (d)

As illustrated in FIG. 8, the step (d) is a step of sealing the batterycase. In the step (d), an upper thermal fusion member 320 is disposed inthe opening groove 122 c of the upper inner sealing part 122 b, and alower thermal fusion member 310 is disposed in the insertion groove ofthe lower inner sealing part 121 b. Then, heat is applied in a state inwhich the upper thermal fusion member 320 is press-fitted in a directionof the lower thermal fusion member 310 to seal the lower inner sealingpart 121 b and the upper inner sealing part 122 b.

Also, heat is applied in a stat in which the lower outer sealing part121 c and the upper outer sealing part 122 d are press-fitted to performthe sealing operation.

Step (e)

As illustrated in FIG. 9, the step (e) is a step of forming athrough-type opening into which the through-hole is inserted. In thestep (e), a bottom surface of the insertion groove of the lower innersealing part 121 b is cut. Thus, the through-type opening 121 a, intowhich the through-hole 110 a is inserted is formed, to complete thesecondary battery 100.

Therefore, in the method for manufacturing the secondary batteryaccording to an embodiment of the present invention, the secondarybattery having the through-type opening may be manufactured, and also,the large space of the through-type opening may be secured to improvethe space utilization.

Accordingly, the scope of the present invention is defined by theappended claims rather than the foregoing description and the exemplaryembodiments described therein. Various modifications made within themeaning of an equivalent of the claims of the invention and within theclaims are to be regarded to be in the scope of the present invention.

1. A secondary battery comprising: an electrode assembly having athrough-hole; and a battery case accommodating the electrode assemblyand having a through-type opening into which the through-hole isinserted, wherein the battery case comprises: a lower case comprising anaccommodation part accommodating the electrode assembly and a lowerinner sealing part having the through-type opening into which thethrough-hole is inserted; and an upper case comprising a cover partcoupled to an upper portion of the lower case to finish theaccommodation part and an upper inner sealing part having a couplinghole to which a front end of the lower inner sealing part is coupled. 2.The secondary battery of claim 1, wherein the upper inner sealing parthas an inner sealing surface having the coupling hole to which the frontend of the lower inner sealing part is coupled and a connection surfacehaving an inner end coupled to a bottom surface of the inner sealingsurface and an outer end connected to the cover part, and an openinggroove is defined between the inner sealing surface and the connectionsurface.
 3. The secondary battery of claim 2, wherein the lower innersealing part disposed on the through-type opening and the inner sealingsurface disposed on the opening groove are press-fitted at the same timeto seal the lower inner sealing part and the upper inner sealing part.4. The secondary battery of claim 1, wherein the front end of the lowerinner sealing part and a top surface of the upper case have the sameheight.
 5. The secondary battery of claim 1, wherein a top surface ofthe upper inner sealing part and a top surface of the cover part havethe same height.
 6. The secondary battery of claim 2, wherein theelectrode assembly comprises a plurality of radical units havingthrough-holes that gradually increase in size, and the plurality ofradical units are stacked upward in order from the radical unit havingthe smallest size to the radical unit having the largest size, and theupper inner sealing part is inserted into a space between an innersurface of the through-hole of the lowermost radical unit and an innersurface of the uppermost radical unit of the radical units.
 7. Thesecondary battery of claim 1, wherein a connection part connecting endsof the lower case and the upper case, which correspond to each other, toeach other is provided.
 8. The secondary battery of claim 7, wherein alower outer sealing part and an upper outer sealing part, which aresealed to each other, are disposed on remaining ends except for the endsof the lower case and the upper case, respectively.
 9. A method formanufacturing a secondary battery, the method comprising: a step (a) ofmanufacturing an electrode assembly having a through-hole; a step (b) ofmanufacturing a battery case comprising a lower case and an upper case,which are folded with respect to an end, wherein the lower casecomprises an accommodation part accommodating the electrode assembly anda lower inner sealing part inserted into the through-hole and having aninsertion groove, and the upper case comprises a cover part finishingthe accommodation part and an upper inner sealing part having a couplinghole to which a front end of the lower inner sealing part is coupled; astep (c) of inserting the electrode assembly between the lower case andthe upper case; a step (d) of sealing the coupled portion between thelower inner sealing part and the upper inner sealing part; and a step(e) of forming cutting a bottom surface of the insertion groove of thelower inner sealing part and a surface of the upper inner sealing part,which are closely attached to each other, to form a through-type openinginto which the through-hole is inserted.
 10. The method of claim 9,wherein the upper inner sealing part has an inner sealing surface havingthe coupling hole to which the front end of the lower inner sealing partis coupled and a connection surface having an inner end coupled to abottom surface of the inner sealing surface and an outer end connectedto the cover part, and an opening groove is defined between the innersealing surface and the connection surface.
 11. The method of claim 10,wherein, in the step (d), the lower inner sealing part disposed on theinsertion groove and the inner sealing surface disposed on the openinggroove are press-fitted at the same time to seal the lower inner sealingpart and the upper inner sealing part.
 12. The method of claim 9,wherein, in step (b), a connection part connecting the lower case to theupper case is disposed on ends of the lower case and the upper case,which correspond to each other, a lower outer sealing part and an upperouter sealing part, which are sealed to each other, are disposed onremaining ends except for the ends of the lower case and the upper case,respectively, and the step (d) further comprises a process of sealingthe lower outer sealing part and the upper outer sealing part.
 13. Themethod of claim 9, wherein the step (a) comprises a step ofmanufacturing a plurality of radical units having through-holes thatgradually increase in size and a step of stacking the plurality ofradical units upward in order from the radical unit having the smallestsize to the radical unit having the largest size.
 14. A battery casecomprising: a lower case comprising an accommodation part and a lowerinner sealing part provided at a center of the accommodation part andhaving a through-type opening; and an upper case comprising a cover partcoupled to an upper portion of the lower case to finish theaccommodation part and an upper inner sealing part having a couplinghole to which a front end of the lower inner sealing part is coupled.15. The battery case of claim 14, wherein the upper inner sealing parthas an inner sealing surface having the coupling hole to which the frontend of the lower inner sealing part is coupled and a connection surfacehaving an inner end coupled to a bottom surface of the inner sealingsurface and an outer end connected to the cover part, and an openinggroove is defined between the inner sealing surface and the connectionsurface.
 16. The battery case of claim 15, wherein the lower innersealing part disposed on the through-type opening and the inner sealingsurface disposed on the opening groove are press-fitted at the same timeto seal the lower inner sealing part and the upper inner sealing part.17. The battery case of claim 14, wherein the lower case and the uppercase comprise a connection part connecting ends of the lower case andthe upper case, which correspond to each other, to each other and alower outer sealing part and an upper outer sealing part, which aresealed to each other and respectively disposed on remaining ends exceptfor the ends of the lower case and the upper case.